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Human brains are growing in size, possibly lowering dementia risk

Did you know your brain is likely larger than your grandparents’? A fascinating new study from UC Davis Health shows that human brain sizes have been steadily growing over generations.

If you were born after the 1930s, your brain is significantly bigger than that of someone born earlier in the 20th century. But before you start bragging about your superior intellect, let’s explore why this size difference matters.

Decoding the brain size

The researchers delved into brain scans from thousands of participants in the Framingham Heart Study. This is a long-term project that has tracked health across multiple generations. This incredible study began in 1948.

The team discovered that people born in the 1970s had an average brain volume 6.6% larger and 15% more brain surface area than folks born in the 1930s.

“The decade someone is born appears to impact brain size and potentially long-term brain health,” explained Dr. Charles DeCarli, lead author of the study and a distinguished professor of neurology at UC Davis.

“Genetics plays a major role in determining brain size, but our findings indicate external influences — such as health, social, cultural and educational factors — may also play a role.”

How do scientists measure brain size?

Let’s talk about two important ways scientists measure the brain’s building blocks:

Intracranial volume (ICV)

Think of ICV as the total amount of space inside your skull – your brain’s house. It also includes the fluid, blood vessels, and other tissues that keep your brain healthy. ICV can give clues about overall brain health. In some cases, a larger ICV might mean a larger brain, suggesting more brainpower.

However, brain size isn’t the whole story – how efficiently your brain works matters too. Doctors and researchers use ICV measurements to track changes in the brain. This can help diagnose conditions like Alzheimer’s disease, where brain tissue may shrink over time.

Surface area

Your brain’s surface area is all about the outer layer, called the cerebral cortex. This part is incredibly wrinkly, with folds and grooves – imagine crumpling a piece of paper to fit more surface area into a small space. Those folds are packed with brain cells (neurons).

More folds mean more brain cells, boosting your thinking power. Different parts of the cortex do different jobs. Some handle your senses, others control how you move, and others tackle complex things like problem-solving and emotions.

Overall, ICV gives a sense of your brain’s overall size and surface area focuses on how complex your brain’s ‘wiring’ can be, like how many rooms are in that house and how they’re connected.

Together, these measurements help us understand individual brain power, explaining why some people’s brains might be better at certain tasks, and also track brain health as we age or if diseases affect the brain.

Brain size and dementia connection

So, why should we care about having a slightly larger brain? Scientists believe it has to do with a concept called “brain reserve.” Imagine your brain as a fortress protecting your mental well-being.

The bigger and stronger the fortress, the more resources (like healthy brain cells) you have to combat the assaults of age-related diseases like Alzheimer’s dementia.

While the total number of people with dementia is growing because we’re living longer, the percentage of the population affected by these diseases is actually decreasing.

“Larger brain structures like those observed in our study may reflect improved brain development and improved brain health,” said Dr. DeCarli. “A larger brain structure represents a larger brain reserve and may buffer the late-life effects of age-related brain diseases like Alzheimer’s and related dementias.”

So, why the growth in brain size?

Scientists have some intriguing theories:

Better nutrition and health

Nutrition is the bedrock of brain development and function. The brain, especially during critical periods of childhood, depends on a healthy diet for growth. Essential nutrients like omega-3 fatty acids, vitamins, and minerals directly support the creation of brain structures and new neural connections.

Adequate nutrition during pregnancy and throughout childhood is vital for proper brain development, affecting everything from brain size to function.

Moreover, access to quality healthcare is equally vital – it ensures that potential health issues that could hinder brain development are caught and treated early. Immunizations, check-ups, and managing illnesses create a healthier environment for young brains to thrive.

Education & mental stimulation

The power of education and mental stimulation in shaping our brains can’t be underestimated. Complex learning tasks and challenges promote neural growth and reinforce the brain’s plasticity – that amazing ability to adapt and form new connections throughout our lives.

Education helps build a “cognitive reserve,” meaning that mentally engaging activities may make our brains more resilient to decline as we age.

Continuously exposing our brains to new information and challenges keeps them fit and flexible – just like exercise does for our bodies. This can lead to stronger brain networks and better overall cognitive function.

Social & cultural changes

Our evolving social and cultural landscapes hold intriguing possibilities for brain development. Research suggests that changes in our society and lifestyles could also influence how our brains grow and adapt.

Digital technology and global connections expose us to a vast array of cultures, ideas, and ways of thinking. This could foster more adaptable brains, ready for a globalized world.

Shifts in how families function and what we value socially may nurture certain types of development. For instance, a focus on emotional intelligence and social skills could enhance the brain regions responsible for empathy and social thinking.

Future directions on brain size and development

This discovery opens exciting possibilities for brain research.

By pinpointing the factors that promote healthy brain development, scientists can create targeted strategies to boost brain resilience from a young age. Imagine interventions that enhance cognitive function throughout life.

Understanding how these factors contribute to larger and more complex brains could also lead to breakthroughs in treating dementia and other neurodegenerative diseases.

New approaches might include nutritional supplements, educational programs designed to stimulate the brain, and therapies that mimic the benefits of a rich social environment. These strategies could revolutionize how we prevent and manage these diseases.

In essence, this research is a game-changer. It challenges our understanding of the brain while offering exciting possibilities for extending cognitive health and improving quality of life as we age. It’s a significant step forward in the fight against dementia, offering a glimmer of hope for a future with sharper minds and healthier brains.

The study is published in the journal JAMA Neurology.


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